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Thomas M. Lehman a; Steven L. Wickba Department of Geosciences, Texas Tech University, Lubbock, Texas, U.S.A. b Division of Science andResource Management, Big Bend National Park, Texas, U.S.A.

Online publication date: 02 December 2010

Lehman, Thomas M. and Wick, Steven L.(2010) ' Chupacabrachelys complexus , n. gen. n. sp.(Testudines: Bothremydidae), from the Aguja Formation (Campanian) of West Texas', Journal of VertebratePaleontology, 30: 6, 1709 1725

10.1080/02724634.2010.520782http://dx.doi.org/10.1080/02724634.2010.520782

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Journal of Vertebrate Paleontology 30(6):17091725, November 2010 2010 by the Society of Vertebrate Paleontology

ARTICLE

CHUPACABRACHELYS COMPLEXUS , N. GEN. N. SP. (TESTUDINES: BOTHREMYDIDAE),FROM THE AGUJA FORMATION (CAMPANIAN) OF WEST TEXAS

THOMAS M. LEHMAN *,1 and STEVEN L. WICK 21Department of Geosciences, Texas Tech University, Lubbock, Texas 79409, U.S.A., [email protected];

2Division of Science and Resource Management, Big Bend National Park, Texas 79834, U.S.A., [email protected]

ABSTRACT Chupacabrachelys complexus , n. gen. n. sp., is an unusual bothremydid pleurodire of the tribe Taphrosphyinifound in theCampanian Aguja Formation in theBig Bend regionof West Texas. Thetypeexampleis oneof themostcompletebothremydid specimens known. Its skull and lower jaw are very narrow, triangular, and dorsoventrally compressed, with thecoronoid process posterior to midlength of the jaw. The orbits are elongate anteroposteiorly with narrow extensions alongthe maxilla-prefrontal sutures, and rugose maxillary projections at the anterolateral corners of orbits. Its reduced temporalemargination, weak posteroventral ange on the squamosal, weak lateral extension of the squamosal along the quadratesuture, and posteroventral knob on opisthotic suggest afnity with Taphrosphyini. The shell has six neurals and a nuchal

with sharp midline embayment, and is nearly identical to those of Chedighaii and Bothremys . Chupacabrachelys providesadditional evidence for the dramatic evolutionary radiation of bothremydid turtles in tropical paralic environments duringLate Cretaceous time.

INTRODUCTION

Pleurodira or side-necked turtles are today a relict group of low diversity, restricted to freshwater habitats in the southernhemisphere. However, during Late Cretaceous and Paleogenetime, pleurodires were taxonomically diverse, inhabited a vari-ety of environments, and had a nearly worldwide distribution(Gaffney et al., 2006). Much of the early literature on fossil pleu-rodires focused on their relatively conservative shell morphology;it was only the recent discovery of many well-preserved skulls

that revealed the magnitude of pleurodire diversity. The extinctfamily Bothremydidae was among the most widespread of pleu-rodire groups during their Late Cretaceous and Paleogene acme.Bothremydids have distinctive skulls with wide prefrontals, andin contrast to other pleurodires, have very little cheek emargina-tion retaining a maxilla-quadratojugal contact. Many also possess jaws with unique triturating surfaces indicative of highly special-ized feeding strategies. In a monographic study of bothremydids,Gaffney et al. (2006) recognized four distinct clades (Kurmade-mydini, Cearachelyini, Bothremydini, and Taphrosphyini), whichthey ranked as tribes.

Fragmentary specimens of bothremydid turtles are commonin coastal facies of the Upper Cretaceous Aguja Formation inthe Big Bend region of West Texas. Most of these (e.g., TMM43469-1) consist of isolated shell fragments, originally identi-ed doubtfully as ? Taphrosphys (Lehman, 1985) and later asBothremys (Lehman, 1997; Tomlinson, 1997). However, noneof these many fragmentary specimens is sufciently completeto condently identify. In 2005 the authors recovered a com-plete bothremydid shell, and a second nearly complete skele-ton with skull and jaws. These specimens represent a new genusand species of bothremydid, Chupacabrachelys complexus . It islikely that much of the fragmentary material recovered pre-viously from the Aguja Formation may also belong to thisspecies.

*Corresponding author.

The type specimen of Chupacabrachelys complexus (TMM45606-1) was collected on the Ten Bits Ranch, north of StudyButte, Texas (Fig. 1). It is remarkably complete, more so thanmany other Cretaceous bothremydids, and is missing only thehind limbs. As a result, in the present paper most of the axial andappendicular elements are described and illustrated from multi-ple perspectives. The referred specimen (TMM 45856-1) was re-covered from the same stratigraphic interval as the type, about 24km south in Big Bend National Park (Fig. 1). Other than the shell,the referred specimen has two elements (coracoid and humerus)that can be compared with the holotype. The shells of both spec-imens have most of the sutures evident on their visceral surfaces,but scute sulci can only be delineated in places. Both appear tobe adult individuals; however, the type specimen is only aboutthree-fourths the size of the referred specimen (measurements inAppendix 1). Although it seems likely that the referred specimenpertains to Chupacabrachelys complexus , the shells of some both-remydids ( Chedighaii , Bothremys ) are nearly identical to eachother and to Chupacabrachelys complexus , and so we cannot becertain in the referral. Therefore, in the following description, thefeatures of the referred specimen not clearly evident in the type(nuchal notch, form of mesoplastra) are noted separately. Chu- pacabrachelys complexus will be compared below primarily withthe well-known bothremydids Chedighaii and Bothremys , whichhave shells remarkably like that of Chupacabrachelys , but radi-

cally different skulls.Geologic Setting The Aguja Formation consists of aneastward-thinning wedge (135 to 285 m) of paralic and marinesandstone interbedded to the west with mudstone and lignite de-posited in terrestrial coastal plain environments (Lehman, 1985;Fig. 1). The Aguja Formation is underlain by marine shale of thePen Formation, and the two units intertongue to the east. Twomajor depositional sequences are recorded in these deposits, thelower of which is present only in the western Big Bend region.

Lehman (1985) informally subdivided the Aguja Formationinto several members. The basal sandstone member consistsof progradational deltaic and littoral facies. It is overlain bythe terrestrial lower shale member, which includes interbedded

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FIGURE 1. Locality map and cross-section showing stratigraphy of the Upper Cretaceous Pen and Aguja Formations in southwestern Texas. Thestratigraphic positions of Texas Memorial Museum (TMM) Chupacabrachelys complexus collection sites on Ten Bits Ranch (XB) and near Rat-tlesnake Mountain (RM) in Big Bend National Park are shown. Symbols on stratigraphic columns show intervals with ostreid bivalves and Ophiomor- pha burrows.

sandstone, carbonaceous shale, and lignite. A transgressive ma-rine sandstone, the Rattlesnake Mountain sandstone member,overlies the lower shale (Lehman and Tomlinson, 2004). Awestward-thinning marine shale unit (informally referred to asthe McKinney Springs tongue of the Pen Formation) is inter-posed within the Aguja. Overlying this marine shale are depositsof the second depositional sequence of the Aguja, extensive over

the entire Big Bend region and adjacent Mexico. The TerlinguaCreek sandstone member is overlain by the upper shale member,which is comprised of sandstone, mudstone, and carbonaceousshale accumulated in coastal environments.

The type and referred specimens of Chupacabrachelys complexus were collected from the base of the upper shale mem-ber (Fig. 1), about 1 m (TMM 45856-1) to 5 m (TMM 456061)


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LEHMAN AND WICKBOTHREMYDID TURTLE FROM TEXAS 1711

FIGURE 2. Quarry diagram showing holotype specimen of Chupacabrachelys complexus (TMM 456061) as preserved. Skeletal elements found

beneath others are shaded. Current ripple cross-lamination 10 cm above bone-bearing horizon indicates northwesterly ow during deposition.

above the top of the Terlingua Creek sandstone. Most of the fos-sil vertebrates of the Aguja Formation, including the two spec-imens of Chupacabrachelys complexus , were collected from thisintervalthe lower part of the upper shale member (reviewed byRowe et al., 1992; Lehman and Busbey, 2007). Ammonite bios-tratigraphy (Waggoner, 2006), vertebrate biostratigraphy (Roweet al., 1992), and radiometric age determinations (Befus et al.,2008) indicate that the upper shale member is Middle to LateCampanian (Judithian) in age. Exact locality information forboth specimens is available at the Vertebrate Paleontology Lab-oratory of the Texas Memorial Museum in Austin, Texas.

Taphonomy TMM 456061 was preserved in the base of avery ne-grained cross-laminated sandstone bed with thin dis-continuous layers of carbonaceous clay (Fig. 1). No remains of any other vertebrates were found at the site. All parts of TMM456061 were preserved on the same horizon, disarticulated, withmost of the larger elements in a horizontal attitude; smaller el-ements were jumbled and inclined at varied angles (Fig. 2). Theplastron was preserved upright, probably close to where the car-cass had originally rested. Most of the small appendicular andaxial elements were displaced to the north and west. The lower jaw was detached from the skull. The inverted carapace had sep-arated into anterior and posterior halves along the third costals,covering the skull and other elements. The missing parts of thenuchal, and right anterior peripheral bones, were lost due to mod-

ern erosion; they were exposed when the specimen was discov-ered (Figs. 2, 3). There is no indication that predation or scav-enging was responsible for dismemberment of the carcass. Theskeletal elements show little distortion due to compaction, in-cluding the carapace and plastron, which preserve their naturalcurvature.

The referred specimen (TMM 45856-1) was preserved in athick claystone (Fig. 1). It consists of a nearly complete shell, pre-served in articulation with the pelvis and resting on the plastron.There are several partially healed conical punctures and long lin-ear gouges in the carapace (Fig. 3). The anterior end of the plas-

tron was also broken and partly healed later in life. Judging fromthe broad form and spacing of the bite marks, the unsuccessfulpredator in this case was probably Deinosuchus , whose remainsare preserved in the same facies of the Aguja Formation (e.g.,Schwimmer, 2002). Only a few appendicular elements are pre-served (humerus, coracoid, metatarsal, and a phalanx), protectedinside the shell and resting on the visceral surface of the plastron.The posterior carapace margin is encrusted with small oysterspat, and parts of both carapace and plastron are crossed by nearcuate grazing trails. Although the anterior end of the carapaceretains its natural curvature, the rest of the shell is attened. Thestratigraphic position of both TMM 45856-1 and TMM 456061, just above the paralic Terlingua Creek Sandstone, and the pres-ence of ostreid bivalves and selachian remains in nearby deposits


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FIGURE 4. Chupacabrachelys complexus , n. gen. n. sp., skull of TMM 456061 in A , dorsal, B, ventral, C, right lateral, and D , anterior views;and lower jaw in E , dorsal, F, right lateral, and G , medial views; broken surfaces (cross-hatched), areas covered by sediment matrix (white), andphotographs for comparison. Inset diagram provides restoration of skull in dorsal view with extent of visible sutures (and mirror image) shown;asymmetry and distortion of left side removed. Abbreviations : ang , angular; art , articular; cor , coronoid process; den , dentary; fm , fossa meckelii;fr , frontal; in , internal nares; j, jugal; lab , labial ridge; lin , lingual ridge; ma , mandibular articulation; mx , maxilla; op , opisthotic; p , parietal; pmx ,premaxilla; po , postorbital; pra , prearticular; prf , prefrontal; ptr , pterygoid trochlear process; q , quadrate; qj , quadratojugal; scm , sulcus cartilaginousmeckelii; sym , mandibular symphysis; sq , squamosal.

(Fig. 1) suggest a coastal environment for Chupacabrachelys , andis consistent with the brackish water habitat interpreted for manyother North American fossil pleurodires (Gaffney and Zangerl,1968).

Institutional Abbreviations ALAB , Alabama Museum of Natural History, Tuscaloosa; ANSP , Academy of Natural Sci-ences, Philadelphia; FMNH , Field Museum, Chicago; TMM ,Texas Memorial Museum, Austin; YPM , Yale Peabody Museum,New Haven.

DESCRIPTION

Order TESTUDINES Linnaeus, 1758Infraorder PLEURODIRA Cope, 1864

Superfamily PODOCNEMIDOIDEA Cope, 1868Family BOTHREMYDIDAE Baur, 1891

Tribe TAPHROSPHYINI Gaffney et al., 2006CHUPACABRACHELYS , new genus


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FIGURE 6. Comparison of selected Bothremydidae lower jaws in lateral and dorsal views, standardized to comparable length with triturating sur-faces (gray) and mandibular articulation (cross-hatched) highlighted. Scales on right show four ratios of standard jaw measurements and variation inangle between jaw rami for bothremydids: Araiochelys hirayamai (Ah), Bothremys cooki (Bc), Bothremys maghrebiana (Bm), Bothremys sp. FMNHPR247 (Bs), Bothremydini indet. AMNH 29989 (Bi), Chendighaii barberi (Cb), Chupacabrachelys complexus , n. gen. n. sp. ( Cc), Cearachelys placidoi(Cp), Foxemys mechinorum (Fm), Kurmademys kallamedensis (Kk), Labrostochelys galkini (Lg), Rhothonemys brinkmani (Rb), Taphrosphys con- golensis (Tc), and Taphrosphys ippolitoi (Ti). Markers on scales for Taphrosphyini are shown in gray, jaw reconstructions are modied from Gaffneyet al. (2006), and ratios are based on measurements given by Gaffney et al. (2006).

Gaffney and Forster, 2003). There are no triturating pits or pos-terior expansions of the triturating surface as in typical Bothre-mydini.

The contacts of the dentary with postdentary elements are dif-cult to delineate; the sutures between angular, surangular, andarticular appear to be completely fused. The dentaries are widely

exposed on the lateral surface of the jaw, relative to the coronoidand surangular. Preservation is inadequate to reveal the pres-ence or location of the foramen nervi auriculotemporalis. Thesulcus cartilaginis meckelii is a distinct groove reaching anteri-orly almost to the symphysis. The prearticular and angular areseparated by a narrow opening that extends posteriorly from thesulcus cartilaginis meckelii (Fig. 4), and the two elements do notshare a contact. Although this separation appears to be natural,it might be due to postmortem compression; the angular is aredoutward on the lateral side of the jaw. The splenial is absent. Thedorsal opening of fossa meckelii is a narrow slit, poorly exposedin dorsal view. There is a low midline longitudinal ridge on themandibular articulation surface. The retroarticular process is welldeveloped and posteriorly directed (not ventrally directed as in

Podocnemididae), and has a small foramen (foramen posteriuschorda tympani) on its dorsal surface.

Postcranial Skeleton

Cervical Vertebrae Parts of four cervical vertebrae are pre-

served (Fig. 7). These are (1) the atlas, lacking the right half of the neural arch; (2) the centrum of a mid cervical; (3) a completeposterior cervical (centrum and neural arch were preserved sep-arately, but the two t together and appear to comprise a singlevertebra); and (4) the centrum of the eighth cervical (preservedseparately from the neural arch of the eighth, which remains inarticulation with the carapace).

The atlas centrum is amphicoelus and appears to be fused withthe intercentrum (Fig. 7A). A remnant notochordal pit is presenton the posterior face of the centrum. There is a thin keel on theventral surface, expanded to form a nub on the posterior end.Only the left half of the neural arch is preserved. Its anterior endforms part of the articular facet for the occipital condyle. Thelateral surface appears to have a remnant articulation surface for


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FIGURE 7. Chupacabrachelys complexus , n. gen. n. sp., vertebrae of TMM 456061; atlas in A , posterior, B, left lateral, and C , ventral views; centrumof ?fourth cervical in D , posterior, E , left lateral, and F, ventral views; ?seventh cervical in G , posterior, H , left lateral, and I, ventral views; centrum of eighth cervical in J , posterior, K , left lateral, and L, ventral views; anterior caudal vertebra in M , left lateral and N , ventral views. Inset line diagramsshow the atlas, seventh cervical, and caudal vertebrae of Podocnemis expansa (modied from Williams, 1950; Gaffney, 1990) reduced to commonheight.

an atlantal rib. The posterior end bears a small, medially directedpostzygopophysis.

The centra for the mid and posterior cervicals are all pro-coelous, taller than wide, and compare well in general form withthose of Podocnemis expansa (Williams, 1950). None of the artic-ulation surfaces of the centra appear to have saddle joints butall have a strong ventral keel expanded at anterior and poste-rior ends to form an accessory ball-socket articulation, similar tothose in Podocnemis expansa (Williams, 1950). The posterior ar-ticulation of the eighth cervical centrum is more expanded later-ally than the others (Fig. 7L). The anteroventral rim of each cen-trum bears low parapophyseal protuberances. All of the centrahave oval depressions on their lateral surfaces. The diapophysesare comprised of both centrum and neural arch, and are relatively

short compared to Podocnemis expansa (Williams, 1950). Theneural arch of the complete posterior cervical (Fig. 7G) is rela-tively taller than in Podocnemis expansa , but the postzygapophy-ses are elevated, close together at the posterior end of the neuralspine, and separated by a deep pit, as in the seventh cervical of Podocnemis expansa (Williams, 1950).

Thoracic Vertebrae The rst two thoracic vertebrae are pre-served in articulation with the carapace, the third is preservedseparately, the fourth and fth are in articulation, and the re-mainder are not preserved. All of the thoracic vertebrae have atarticulation surfaces and compressed hourglass-shaped centra.The anterior end of the rst thoracic centrum is more expandedlaterally for articulation with the rib heads than any of the others.

The fourth and fth centra are twisted as a result of a pathologicalshell abnormality (doubling of the fth costal on the left side).

Caudal Vertebrae Parts of at least 10 caudal vertebrae arepreserved; all have procoelus articulations. The proximal caudalshown here (Fig. 7M) is typical of the entire series, and muchlike the fth caudal of Podocnemis expansa illustrated by Gaffney(1990).

Scapula The scapula (Fig. 8) matches the description forTaphrosphys sulcatus (as given by Gaffney, 1975) with a longercylindrical dorsal process, slightly curved medially, and shorterventral (acromial) process tapering distally. The angle of 92 between the two processes is closer to Taphrosphys (98 ) thanPodocnemis (77 given by Gaffney, 1975). The left scapula waspreserved in articulation or nearly so with the rst thoracic rib on

costal 1 (Fig. 2).Coracoid The coracoid (Fig. 8) is almost perfectly intermedi-ate in form between those of Podocnemis expansa and Taphros- phys sulcatus (as compared by Gaffney, 1975). The shaft is broadand C-shaped in cross-section, and relatively short (shorter thanin Podocnemis , but not as short as in Taphrosphys ), broad andcurved (more so than in Podocnemis , but not as curved as inTaphrosphys ), and with a large scapular articulation (larger thanin Podocnemis , but not as large as in Taphrosphys ). The coracoidin the referred specimen (TMM 45856-1) is identical to that of the holotype.

Humerus The humerus (Fig. 8) is similar to that of Podoc-nemis expansa (illustrated by Gaffney, 1990), Bothremys barberi


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FIGURE 8. Chupacabrachelys complexus , n. gen. n. sp., forelimb elements of TMM 456061; left coracoid in A , lateral, B , ventral, and C, dorsalviews; left scapula in D , anterior and E , lateral views; right humerus in F, dorsal, G , ventral, and H , anterior views; right radius in I, dorsal, J ,ventral (showing proximal articulation surface), and K , medial views; left ulna in L , dorsal (showing proximal articulation surface), M , ventral, andN , medial views. Inset diagrams compare humerus, coracoid, articulated ulna and radius of Chupacabrachelys complexus with Taphrosphys sulcatus(modied from Gaffney, 1975), Chendighaii barberi (from Zangerl, 1948), and Podocnemis expansa (from Gaffney, 1990) reduced to common length.Abbreviations : acr , acromion process; bic , bicipital tendon attachment; cor , articulation for coracoid; ect , ectepicondylar foramen; gle , glenoid; int ,articulation for intermedium; lat , lateral process; lig, radio-ulnar ligament attachment; med , medial process; ole , olecranon process; sca , articulationfor scapula; scp , scapular spine; uln , articulation for ulnare

(CNHM P27405; illustrated by Zangerl, 1948), and Taphrosphys sulcatus (YPM PU 18707; illustrated by Gaffney, 1975). Its fea-tures are intermediate between the slender form with a short me-dial process and narrow distal end observed in Podocnemis andBothremys , and the more robust form, with a wide medial processand wide distal end found in Taphrosphys . Although the distalend appears to be more expanded than in Bothremys , the ratioof distal width to total length is 0.3 (as in Podocnemis ; Gaffney,1975, and in Bothremys based on illustration given by Zangerl,1948) but not as wide as in Taphrosphys (0.47). Other differencesare also subtle. The head is relatively small and more in line withthe shaft (as in Bothremys ), rather than large and set out at a rightangle to the shaft (as in Taphrosphys and Podocnemis ). The val-

ley between medial and lateral processes on the ventral side isnot as deep as in Taphrosphys and Podocnemis . The acute ridgeextending from the base of the medial process to capitellem onthe ventral side of shaft noted by Zangerl (1948) in Bothremys islacking. Although the area around the ectepicondylar foramen isbroken, it is better preserved in the humerus found with the re-ferred specimen (TMM 45856-1). In both cases, the foramen ap-pears to be a more fully enclosed groove, rather than the shallowgroove in Bothremys , but not asdeepasin Podocnemis . There areslightly depressed, ovoid muscle insertion scars on the humeralshaft at the base of the deltopectoral crest (for deltoideus), andat the base of the lateral process adjacent to the head (for latis-simus dorsi).


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Ulna and Radius Both the ulna and radius are similar in formto Podocnemis expansa (illustrated by Gaffney, 1990), althoughrelatively shorter and with more expanded distal ends (Fig. 8).The proximal end of the radius has a cup-shaped humeral articu-lation surface, slightly larger in diameter than the shaft. There is aprominent attachment site for the superior radio-ulnar ligament just below the humeral articulation (Gaffney, 1990). The proxi-mal end of the ulna has a very shallow sigmoid notch and olecra-non extending only slightly above the humeral articulation. Thebicipital tubercle (Walker, 1973) lies close to the humeral articu-lation surface. The broad carpal articulation surface has two dis-tinct faces, one directed medially for the intermedium, the otherdistally for the ulnare. The broad and attened distal expansionsof radius and ulna suggest that Chupacabrachelys may have had awebbed manus as in some extant and fossil pelomedusoids (e.g.,Fielding et al., 2005). However, only a few metacarpals are pre-served, and these are not elongate compared to Podocnemis expansa .

Tarsus and Metatarsals The preserved parts of the tarsus andpes are remarkably similar in form to those of Podocnemis expansa (illustrated by Gaffney, 1990). Elements of the right hindfoot were found disarticulated but closely associated (Fig. 9).The astragalus has a complex, proximal saddle-shaped articula-tion surface and a gently convex distal surface. There are sev-eral isolated distal tarsals, one of which may be distal tarsal 4.This tarsal is cylindrical in form with articulation facets on foursides, and a shallow concavity on the presumed anterior surface.Metatarsals I through IV, with placement interpreted by gradualincrease in length and similarity in form with those of Podocne-mis expansa (Gaffney, 1990), have curved shafts and asymmetricproximal ends that would overlap in articulation. The distal ar-ticulation surfaces are well developed on metatarsals I throughIII, but less distinct on IV. Metatarsal V is a square plate witha distinct articulation facet for distal tarsal 4 and a prominentknob for articulationwith phalanx V-1. Of the isolated phalanges,only phalanx V-1 can be identied; it is comparable in length tometatarsal IV but slender and curvedvery much like that of Podocnemis expansa (Gaffney, 1990).

Unguals The ungual phalanges are broad, thin, and paddle-

shaped as in Taphrosphys sulcatus (Gaffney, 1975). All were pre-served separately and cannot be condently assigned to fore- orhind limb or digit; however, examples span a range in size andshape (Fig. 9). Some are relatively narrow and slightly constrictedbelow the proximal articulation surface; others are broad andmore constricted at the articulation surface. Based on the similararrow-shaped unguals in Araripemys barretoi (Meylan, 1996), thelarger broad unguals likely belong to digit I, II, or III, whereas thesmaller narrow ones are from digit IV or V. The wide and shal-low articulation surfaces suggest that the unguals were capable of only a limited range of exion.

Pelvis Both innominates are preserved in TMM 456061, theleft side completely (although the ischium was found detached).Both are also preserved in articulation in the referred specimen(TMM 45856-1), but dorsoventrally crushed. The general form of the pelvis is very much like Podocnemis expansa (illustrated byGaffney, 1990). The ilium and pubis are united, with only a faintsuture visible between them within the acetabulum (Fig. 10).The prepubis appears to be shorter than in Podocnemis expansa ,but the end is missing or unnished. However, the prepubis iscompletely preserved in the companion specimen. It is a shortremnant triangular process as restored here (Fig. 10), and as inBothremys barberi (FMNH P27370; Zangerl, 1948). The prepubicprocesses did not meet on the midline, unless they were extendedin cartilage. Similarly, the posteroventral part of the ischium isexpanded to form an arcuate articulation with the plastron. In thereferred specimen(TMM 45856-1), the plastral articulationof theischium extends anteromedially, but does not meet the oppositeischium along the midline. The iliac surface for articulation with

FIGURE 9. Chupacabrachelys complexus , n. gen. n. sp., hind foot ele-ments of TMM 456061 in dorsal view; A , right metatarsal V, B, distaltarsal ?IV, C , right astragalus, D , right phalanx V-1, E , left metatarsal IV,F, left metatarsal III, G , left metatarsal I, H , several ungual phalangesshowing variation in form. Inset diagram shows reconstruction of righthind foot in dorsal view, based on Podocnemis expansa (modied fromGaffney, 1990). On metatarsal V articulations are shown for distal tarsalIV (dt IV), metatarsal IV (mt IV), and phalanx V-1 (p V-1).


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FIGURE 11. Chupacabrachelys complexus , n. gen. n. sp., preserved elements of shell in TMM 456061 with carapace in A , dorsal and B , visceralviews showing cross-sections of bridge peripherals; and plastron in C , ventral and D , visceral views. Inset diagrams show anterior lobe of plastron inE , TMM 456061 and F, TMM 45856-1 compared with several specimens of Chendighaii barberi (from Zangerl, 1948; Gaffney and Zangerl, 1968);

restoration of shell in G , dorsal, H , ventral, and I, right lateral views, based on both TMM 456061 and 45856-1, showing sutures and scute sulciobserved on both specimens (with mirror image); abnormalities and asymmetry removed.

The ornamentation of the carapace consists of the typi-cal pelomedusoid pattern of ne reticulate and discontinuousbranching polygonal grooves. The ne grooves are not deeply in-cised (as in some specimens of Taphrosphys ; Gaffney, 1975) andare only obvious in oblique illumination. In the larger referredspecimen (TMM 45856-1), the ornamentation is more sharply de-ned.

Plastron The plastron is shorter than the carapace; however,when the carapace is restored to its natural curvature, the plas-tron extends slightly anterior to the front edge of the carapace(Fig. 11). The form of the plastron, the proportions and relation-ships of each of its elements, are nearly identical to that in Both-remys barberi (Gaffney et al., 2006). The anterior edge is semi-circular; the bridge is longer than the anterior lobe and shorter


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than the posterior lobe, with lateral margins tapering posteriorly;the anal notch is deep and U-shaped. Sutures for the mesoplastraare not visible in the holotype (obscured by a thin crust resistantto preparation), but they are well dened in the referred speci-men (TMM 45856-1). The entoplastron is longer than wide in thetype (as in some specimens of Bothremys barberi e.g., ANSP15902; Gaffney et al., 2006where in most cases the entoplastronis wider than long), but in the referred specimen (TMM 45856-1)the entoplastron is broader. The entoplastron in the companionspecimen also has a medial ridge on its visceral surface (smoothin the type specimen). The epiplastra have slight bulges on theirvisceral surface; these aremuch more pronounced on the referredspecimen, which also has a midline notch between the epiplastra(Fig. 11). The lateral margins of the posterior lobe have a slightlythickened lip that extends back from the inguinal buttresses.

The pubic scar is oval; the ischiac scar is triangular and wellforward of the posterior margin of the plastron. The right andleft ischiac scars are joined by a low transverse ridge parallel tothe border of the anal notch. The scale sulci are only partly visi-ble in both type and referred specimens, but appear to also be likethose in Bothremys barberi . The intergular scale extends onto theanterior part of the entoplastron, whereas the gular scale is small,triangular, and restricted to the epiplastron. The sulcus betweenhumeral and pectoral scales is posterior to the epi-hyoplastral su-ture. The sulcus between pectoral and abdominal scales crossesthe anterior part of the mesoplastron and posterior part of thehyoplastron, whereas the sulcus between abdominal and femoralscales crosses the anterior part of the hypoplastron, and the sul-cus between femoral and anal scales crosses the xiphiplastron ata slight angle. Preservation is insufcient in both specimens todetermine whether the pectoral scale reached the entoplastron.There is no obvious ornamentation on the external surface of the plastron. However, on the larger referred specimen (TMM45856-1), the same pattern typical of the carapace extends ontothe bridge and along the margins of anterior and posterior lobesof the plastron.

Shell Proportions The shells of Bothremys and Chedighaiiare strikingly similar to each other, and a considerable effort hasbeen made to distinguish the two (Gaffney et al., 2006; 2009).

The shell of Chupacabrachelys resembles both of these, and be-cause isolated shells are commonly preserved without diagnosticcranial material, it is appropriate to reexamine shell features thatmay distinguish them.

Zangerl (1948) provided a complete set of over 80 shell mea-surements for each of ve specimens later referred to Bothre-mys and Chedighaii (Gaffney et al., 2006; 2009). Zangerl (1948)standardized the shell measurements relative to the width of thenuchal for each specimen (measurement of character 100/max-imum width of nuchal). A comparable set of measurements isgiven here (Appendix 1) for the type and referred specimensof Chupacabrachelys complexus , and standard ratios can be cal-culated in the same way. The referred specimen (TMM 45856-1) is slightly larger than any of the ve measured by Zangerl(1948) but is similar in size to several described later (ANSP15902, Gaffney and Zangerl, 1968; ALAB PV2001.2, Gaffney etal., 2009). Nearly all of the 80 shell indices for both specimensof Chupacabrachelys , standardized to nuchal width, fall withinthe range reported for specimens measured by Zangerl (1948).Only two proportional features evident in both the type and re-ferred specimens fall outside the range reported for Bothremysand Chedighaii shells. Standardized to nuchal width, these are (1)a relatively narrow entoplastron, and (2) a relatively deeper analnotch (length of posterior wings as given by Zangerl, 1948).

Gaffney and Zangerl (1968) recognized three subtly differ-ent shell types, at that time hypothesized to represent AtlanticCoastal Plain, Gulf Coast, and Western Interior subspecies of Bothremys , and distinguished primarily on the basis of the rel-ative lengths of the nuchal, mesoplastron, and epiplastral sym-

physis. The shell in Chupacabrachelys resembles their AtlanticCoast subspecies (e.g., ANSP 15092), which has bridge periph-erals with ventral plates about half as long as the dorsal plates,and a thick ventral ridge parallel to the posterior edge of thecarapace. However, these features were not considered signi-cant when Gaffney et al. (2006) later tabulated shell criteria fornine specimens of Bothremys and Chedighaii .

Gaffney et al. (2009) found that a shell condently attributedto Chedighaii (ALAB PV 2001.2) has a plastron with a straightanterior margin, swollen epiplastra, and a wide entoplastron witha straight posterior margin. Other shells (FMNH P27369, YPM3608) share these features but were not preserved with diagnos-tic cranial material. In contrast, a shell condently attributed toBothremys (FMNH PR 247) has a semicircular anterior plastronmargin, thin epiplastra, and an entoplastron with a pointed pos-terior margin. Some isolated shells (FMNH 26055, 27370) alsoshare these features.

However, the holotype of Chupacabrachelys exhibits thesmoothly rounded anterior plastron margin thought to be di-agnostic of Bothremys , whereas the larger referred specimenexhibits the truncated plastron margin with swollen epiplastrathought to be diagnostic of Chedighaii (Fig. 11). This disparitylends credence to Zangerls (1948) notion that the latter condi-tion may be attributable to advanced age. With the specimenspresently available, it may not be possible to distinguish onto-genetic and individual variation from features having taxonomicsignicance. Only the form of the entoplastron remains a possiblediscriminating feature; the entoplastron is relatively long and nar-row in Chupacabrachelys , broad but posteriorly pointed in Both-remys , and abruptly truncated posteriorly in Chedighaii .

DISCUSSION

Gaffney et al. (2006) recently conducted an exhaustive phylo-genetic analysis of side-necked turtles, based on 175 charactersin more than 40 taxa, and focused particularly on bothremydids.Their analysis provides a comprehensive framework in which toevaluate the likely relationships of Chupacabrachelys , and as aresult a similar investigation is unnecessary here. Moreover, their

analysis makes it clear that Chupacabrachelys is a member of Bothremydidae, but its further relationships will remain uncleardue to obscuration of several key characters (see below).

Chupacabrachelys exhibits several features considered synapo-morphic for Pleurodira in most phylogenetic analyses (e.g.,Gaffney et al., 2006). These include the pterygoid trochlear pro-cess, the expanded dorsal process of the ilium situated close tothe shell midline and in sutural articulation with the costals, thesutural articulation of the pubis and ischium with the xiphiplas-tron, and the anal notch in the plastron. Additional characters areshared with Eupleurodira: procoelous caudal articulations, neu-rals posterior to second are hexagonal in shape with anterolateralcontacts shorter than posterolateral contacts, equidimensionalmesoplastra not meeting on midline, axillary process of hyoplas-tron reaches third peripheral, elevated cervical postzygapophy-ses, and with Pelomedusoides: nasals absent, prefrontals meetingon midline, splenial absent, cervical vertebrae procoelous, ante-rior plastral lobe reaches anterior carapace margin. Collectively,these features indicate that Chupacabrachelys is a pelomedusoidpleurodire.

Among pelomedusoids, Chupacabrachelys has clear afnitieswith family Bothremydidae. In their revised diagnosis for thefamily, Gaffney et al. (2006) relied exclusively on cranial charac-ters; of these, several diagnostic bothremydid characters are evi-dent in Chupacabrachelys , including (1) a maxilla-quadratojugalcontact is present, in contrast to all other pleurodires (exceptTaphrosphyini); (2) the paroccipital process does not project pos-terior to the squamosal, in contrast to all other Pelomedusoides;and (3) the lingual ridge on the lower jaw is relatively high.


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In addition, the neural series is reduced, extending only to thesixth costals (as in the bothremydids Bothremys and Chedighaii ).These features indicate that Chupacabrachelys is a member of family Bothremydidae.

Gaffney et al. (2006) subdivided bothremydids into severalmore exclusive groups (subfamilies, infrafamilies, tribes, and sub-tribes), in part following Baur (1891) and reecting informalgroups recognized by previous authors (e.g., Antunes and Broin,1988). Several features identied in the phylogenetic analysis of Gaffney et al. (2006) that are present in Chupacabrachelys areconsidered synapomorphic for Bothremydodda (tribes Bothre-mydini + Taphrosphyini) or shared by most members of thisgroup, including (1) an open fossa meckelli (prearticular-angularcontact is short, or perhaps lacking in Chupacabrachelys ); (2) pre-maxilla protruding anteriorly beyond the labial ridge in ventralview; (3) prefrontals projecting forward to form a midline pro-cess; (4) rst costal more than twice the anteroposterior lengthof the second costal; and (5) a short anterior plastral lobe (al-though also found in the podocnemidid Bairdemys ; Gaffneyet al., 2006).

Features of Chupacabrachelys shared with tribe Bothremydiniinclude (1) the relatively long postorbital (though this may becorrelated with reduced temporal emargination); (2) a wide ovalpubic scar and triangular ischiac scar inset from the xiphiplas-tral edge; (3) shell ornamentation of ne forking and irregu-lar grooves; and possibly (4) the embayed anterior margin of the nuchal (clearly evident in the referred specimen of Chu- pacabrachelys , but not preserved in the holotype). However,Chupacabrachelys lacks typical features of the Bothremys group(subtribe Bothremydina of Gaffney et al., 2006), such as (1) avery broad preorbital part of skull, (2) a maxilla-quadrate con-tact, and (3) paired conical pits on maxillary and dentary triturat-ing surfaces.

Features of Chupacabrachelys shared with tribe Taphrosphyiniinclude (1) the narrow preorbital part of skull, (2) reducedtemporal emargination, and (3) the squamosal with weak pos-teroventral ange and a weak tubercle along its suture with thequadrate (both unique though much better developed in typ-ical Taphrosphyini than in Chupacabrachelys ). However, Chu-

pacabrachelys retains a maxilla-quadratojugal contact (lacking inTaphrosphyini), and lacks the jugal-quadrate contact (present inTaphrosphyini; Gaffney et al., 2006).

The placement of Chupacabrachelys within infrafamily Both-remydodda (Gaffney et al., 2006) is therefore supported by sev-eral unambiguous characters, but it is not possible to clearlyresolve its position within this group. Chupacabrachelys couldbe a member of subtribe Bothremydina that secondarily lostmost of the key Bothremys group cranial features and ac-quired several features similar to those of Taphrosphyini. Insupport of this hypothesis, some of the diagnostic Bothremy-dina cranial features are also lost in Chedighaii , which hasa shell nearly identical to that of Chupacabrachelys . Alter-natively, Chupacabrachelys could be a basal member of tribeTaphrosphyini that acquired several of the cranial features(squamosal posteroventral ange and tubercle) of that clade,but retained a plesiomorphic shell morphology like that inBothremydini. This also seems reasonable, particularly becauseshell features for the entire tribe Taphrosphyini are known onlyfor Taphrosphys . Moreover, the unusal triangular cranial mor-phology of Chupacabrachelys , atypical of bothremydids, is foundelsewhere only in Taphrosphyini.

Of these two possibilities, the most likely seems that Chu- pacabrachelys is a basal member of tribe Taphrosphyini. An-other member of this tribe, Labrostochelys , has broadly simi-lar cranial features to those of Chupacabrachelys , and its shellmorphology is unknown. Compared to Labrostochelys , the pre-frontal in Chupacabrachelys is shorter, the premaxilla does notproject as far anterior to the labial ridge, the external narial open-

ing is not completely divided by the prefrontal and premaxilla,the orbit is relatively much larger, the posterior extension of thesquamosal is shorter, the lateral tubercle on the squamosal issmall, the mandibular condyle is not as far anterior to the occip-ital condyle, and the pterygoid trochlear process is more promi-nent. If Chupacabrachelys is a member of Taphrosphyini, thenseveral purported cranial apomorphies of the clade (presenceof jugal-quadrate contact, absence of maxilla-quadratojugal con-tact) and some shell features (plastron with broad posterior lobe,long narrow pubic scar, round ischiac scar at edge of xiphiplas-tron, carapace with deeply furrowed irregular polygonal orna-mentation, lacking nuchal notch) were only acquired by morederived members of this tribe. Further detailed preparation ornon-invasive imaging of the tympanic cavity, palate, and brain-case in Chupacabrachelys might help better elucidate its tribalafliation.

CONCLUSIONS

Gaffney et al. (2006:652) remarked that pleurodires had amore extensive and more complex evolutionary history than hasbeen realized and that they exhibit a diversity of morpholo-gies indicating a remarkable diversity of feeding and sensorystrategies. The discovery of Chupacabrachelys provides addi-tional evidence of this diversity, and of the dramatic Late Creta-ceous evolutionary radiation of bothremydids in particular. Al-though Chupacabrachelys has several key synapomorphies of Bothremydidae, and with infrafamily Bothremydodda, its tribalafliation is uncertain, largely because it has not been possibleto free the tympanic cavity, palate, and braincase of its sedi-ment matrix. The most likelyhypothesis is that Chupacabrachelysis a basal member of tribe Taphrosphyini. Its shell morphol-ogy is nearly identical to those of Bothremydini (e.g., Bothre-mys , Chedighaii ), but its long narrow skull, with slender tritu-rating surfaces, posteriorly extended squamosal horns with sub-tle ventral anges and lateral tubercles, is like those of Taphros-phyini (e.g., Labrostochelys ). The unusual rugose maxillary ex-crescences have not been described in other turtles. Althoughit is tempting to interpret these features as related in some way

to salt-excreting glands, it would seem that similar osteologicalfeatures should be present in other turtles that inhabit marineenvironments.

Prior to the monographic study of Gaffney et al. (2006:652),most studies of bothremydid turtles had been based largely onshells that among pleurodires in general, and in Pelomedusoidesin particular, is relatively conservative morphologically, maskingthe magnitude of pleurodire diversity. Chupacabrachelys pro-vides a stunning example of this phenomenon. Its shell is sonearly identical to those of Bothremys and Chedighaii , both of which occur in coeval strata, that had they been found togetherthey would have been assigned to the same taxa with little doubt.Their skulls differ so dramatically it is hard to believe they be-long to animals with such similar shells. However, no other tur-tle family exhibits such extreme morphological variation as isfound in the skulls of bothremydids (Gaffney, et. al., 2006). Chu- pacabrachelys provides an additional example of this remarkablevariation.

The occurrence of Chupacabrachelys also offers further sub-stantiation for evident latitudinal biogeographic differences be-tween northern and southern parts of the western interiorprovince during Campanian time (e.g., Lehman, 1997). Bothre-mydid turtles are abundant in Campanian paralic strata alongthe Atlantic and Gulf coastal plain (Schwimmer, 2002) and inTexas. A few specimens have been found in Kansas (Gaffneyand Zangerl, 1968) and in New Mexico (Gaffney et al., 2006),but they are currently unknown farther north (Brinkman, 2003).Bothremydid turtles are also abundant and diverse in Campanianstrata of southern Europe and northern Africa (Gaffney et al.,


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2006), suggesting that their distribution was restricted to tropicalwaters, and did not extend to higher latitudes.

ACKNOWLEDGMENTS

The authors thank W. Langston, Jr., T. Rowe, and L. Murrayof the Texas Memorial Museum for their assistance with speci-mens at the Vertebrate Paleontology Laboratory, D. Corrick and

V. Davila of the Science and Resource Management staff of BigBend National Park for their support of the authors eldworkin the Aguja Formation, and J. Wick and E. Lehman for theirpatient indulgence of the authors paleontological endeavors. E.Gaffney, F. OKeefe, and two anonymous reviewers providedhelpful comments that substantially improved the manuscript. Il-lustrations are the work of T. Lehman.

LITERATURE CITEDAntunes, M. T., and F. de Broin. 1988. Le Cretace terminal de Beira

Littoral, Portugal: remarques stratigraphiques et ecologiques, etudecomplementaire de Rosasia soutoi (Chelonii, Bothremydidae).Ciencias da Terra 9:153200.

Baur, G. 1891. Notes on some little known American fossil tortoises.

Proceedings of the Academy of Natural Sciences of Philadelphia43:411430.Befus, K. S., R. E. Hanson, T. M. Lehman, and W. R. Grifn. 2008. Cre-

taceous basaltic phreatomagmatic volcanism in West Texas: maarcomplex at Pena Mountain, Big Bend National Park. Journal of Vol-canology and Geothermal Research 173:245264.

Brinkman, D. B. 2003. A review of nonmarine turtles from the LateCretaceous of Alberta. Canadian Journal of Earth Science 40:557571.

Brown, A. 2008. Haunted Texas: Ghosts and Strange Phenomena of theLone Star State. Stackpole Books, Mechanicsburg, Pennsylvania,122. pp.

Cope, E. D. 1864. On the limits and relations of the Raniformes. Proceed-ings of the Academy of Natural Sciences of Philadelphia 16:181183.

Cope, E. D. 1868. On the origin of genera. Proceedings of the Academyof Natural Sciences of Philadelphia 20:242300.

Fernandez, M., and Z. Gasparini. 2008. Salt glands in the Jurassic metri-orhynchid Geosaurus : implications for the evolution of osmoreg-ulation in Mesozoic marine crocodyliforms. Naturwissenschaften95:7984.

Fielding, S., Martill, D. M., and Naish, D. 2005. Solnhofen-style soft-tissue preservation in a new species of turtle from the Crato Forma-tion (Early Cretaceous, Aptian) of northeast Brazil. Palaeontology,48:13011310.

Gaffney, E. S. 1975. A revision of the side-necked turtle Taphrosphys sulcatus (Leidy) from the Cretaceous of New Jersey. American Mu-seum of Natural History, Novitates 2571, 24. pp.

Gaffney, E. S. 1990. The comparative osteology of the Triassic turtleProganochelys . American Museum of Natural History, Bulletin 194,263. pp.

Gaffney, E. S., and Forster, C. A. 2003. Side-necked turtle lower jaws(Podocnemididae, Bothremydidae) from the Late Cretaceous Mae-varano Formation of Madagascar. American Museum of NaturalHistory, Novitates 3397, 13. pp.

Gaffney, E. S., and Zangerl, R. 1968. A revision of the cheloniangenus Bothremys (Pleurodira: Pelomedusidae). Fieldiana Geology,16:193239.

Gaffney, E. S., Hooks, G. E., and Schneider, V. P. 2009. New material of North American side-necked turtles (Pleurodira: Bothremydidae).American Museum of Natural History, Novitates 3655, 26. pp.

Gaffney, E. S., Tong, H., and Meylan, P. A. 2006. Evolution of the side-necked turtles: the families Bothremydidae, Euraxemydidae, andAraripemydidae. American Museum of Natural History, Bulletin

300, 698. pp.Gaffney, E. S., Campbell, K. E., and Wood, R. C. 1998. Pelomedusoidside-necked turtles from Late Miocene sediments in southwesternAmazonia. American Museum of Natural History, Novitates 3245,11. pp.

Lehman, T. M. 1985. Stratigraphy, sedimentology, and paleontology of Upper Cretaceous (Campanian-Maastrichtian) sedimentary rocksin Trans-Pecos Texas. Unpublished Ph.D. dissertation, Universityof Texas at Austin, Austin, Texas, 300. pp.

Lehman, T. M. 1997. Late Campanian dinosaur biogeography in theWestern Interior of North America; pp. 223240 in D. L. Wolberg,E. Stump, and G. D. Rosenberg (eds.), Dinofest International, Pro-ceedings of a symposium heldat Arizona State University. Academyof Natural Sciences, Philadelphia.

Lehman, T. M., and A. B. Busbey. 2007. Big Bend Field Trip Field Guide.Society of Vertebrate Paleontology, Fall 2007 Field Trip, 69. pp.

Lehman, T. M., and S. L. Tomlinson. 2004. Terlinguachelys schbecki ,a new genus and species of sea turtle (Chelonoidea: Protostegi-dae) from the Upper Cretaceous of Texas. Journal of Paleontology78:11631178.

Linneaus, C. 1758. Systema Naturae, 10th edition, Volume 1. Stockholm,824. pp.

Meylan, P. A. 1996. Skeletal morphology and relationships of the EarlyCretaceous side-necked turtle, Araripemys barretoi (Testudines:Pelomedusoides: Araripemydidae) from the Santana Formation of Brazil. Journal of Vertebrate Paleontology 16:2033.

Rowe, T., R. L. Cifelli, T. M. Lehman, and A. Weil. 1992. The CampanianTerlingua local fauna, with a summary of other vertebrates from theAguja Formation, Trans-Pecos Texas. Journal of Vertebrate Pale-ontology 12:472493.

Schwimmer, D. R. 2002. King of the Crocodylians. Indiana UniversityPress, Bloomington, Indiana, 220. pp.

Tomlinson, S. L. 1997. Late Cretaceous and early Tertiary turtles fromthe Big Bend region, Brewster County, Texas. Unpublished Ph.D.dissertation, Texas Tech University, Lubbock, Texas, 194. pp.

Waggoner, K. J. 2006. Sutural form and shell morphology of Placen-ticeras, and systematic descriptions of Late Cretaceous ammonitesfrom the Big Bend region, Texas. Unpublished Ph.D. dissertation,Texas Tech University, Lubbock, Texas, 398. pp.

Walker, W. F. 1973. The locomotor apparatus of Testudines; pp. 1100in C. Gans (ed.), Biology of the Reptilia, Volume 4, Morphology D.Academic Press, New York.

Williams, E. E. 1950. Variation and selection in the cervical central ar-ticulations of living turtles. American Museum of Natural History,Bulletin 94:511561.

Zangerl, R. 1948. The vertebrate fauna of the Selma Formation of Al-abama. Part II, the pleurodiran turtles. Fieldiana: Geology Memoirs3:2356.

Zangerl, R. 1969. The turtle shell; pp. 311339 in C. Gans (eds.), Biologyof the Reptilia, Volume 1, Morphology A. Academic Press, London.

Submitted July 22, 2009; accepted June 3, 2010.


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APPENDIX 1. Measurements of the type and referred specimens of Chupacabrachelys complexus are given in millimeters. The skulland lower jaw measurements are taken in the manner of Gaffney et al. (2006:685, 690) and designated with the same capital letters.The shell measurements are given in the manner of Zangerl (1948:3638). , an approximate dimension due to distortion of thespecimen or missing parts.

Skull (TMM 456061)

Length, tip of snout to occipital condyle (A) 104Length, tip of snout to end of sagittal crest (I) 106Length, tip of snout to mandicular condyle (O) 95Height, mandibular articulation to skull roof (G) 43Height, occipital condyle to skull roof (K) 27Transverse width at cheeks (B) 70Transverse width at orbits (H) 50Minimum interorbital width (C) 12Anteroposterior length of orbit (D) 27Dorsoventral width of orbit (J) 13Transverse width of external nares (E) 21Lower jaw (TMM 456061)Sagittal length (B) 87Length of triturating surface (A) 56Width of ramus at coronoid process (C) 6

Carapace (TMM 45856-1 and TMM 456061)

Sagittal length (along curve) 730 550Transverse width (at peripheral 7, along curve) 730 550Nuchal, sagittal length 90 Neural 1, sagittal length 80 Neural 2, sagittal length 55 50Neural 3, sagittal length 60 Neural 4, sagittal length 55 50Neural 5, sagittal length 58 50Neural 6, sagittal length 40 30Suprapygal, length 80 65Pygal, length 84Nuchal, anterior width 70 Neural 1, anterior width 45 Neural 2, anterior width 35 25Neural 3, anterior width 25 21Neural 4, anterior width 20 25Neural 5, anterior width 25 25Neural 6, anterior width 20 25Pygal, anterior width 60 35Suprapygal, posterior width 80Pygal, posterior width 95 75Nuchal, maximum width 155 110Neural 1, maximum width 60 Neural 2, maximum width 50 42Neural 3, maximum width 50 36Neural 4, maximum width 47 35Neural 5, maximum width 45 40Neural 6, maximum width 45 35Peripheral 1, inner length 40 15Peripheral 2, inner length 55 50Peripheral 3, inner length 80 65Peripheral 4, inner length 65 50Peripheral 5, inner length 60 50Peripheral 6, inner length 60 50Peripheral 7, inner length 60 60Peripheral 8, inner length 70 65Peripheral 9, inner length 90 65Peripheral 10, inner length 75 60Peripheral 11, inner length 70 55Peripheral 1, outer length 85 Peripheral 2, outer length 90 Peripheral 3, outer length 95 65Peripheral 4, outer length 85 60Peripheral 5, outer length 80 60Peripheral 6, outer length 80 70Peripheral 7, outer length 90 80Peripheral 8, outer length 105 80Peripheral 9, outer length 100 70Peripheral 10, outer length 85 65Peripheral 11, outer length 85 65Plastron (TMM 45856-1 and TMM 456061)Length, midline to anal notch 540 434Width anterior to bridge 340 235Width posterior to bridge 325 220Length of anterior lobe 125 108Length of posterior lobe on midline 210 163Length of epiplastral symphysis 20 30Length of entoplastron 100 75Length of hyoplastral symphysis 130 90Length of hypoplastral symphysis 140 120Length of xiphiplastral symphysis 145 110Depth of anal notch 62 45Width of entoplastron 75 45Length of hyo-hypoplastral suture 165 105Width of mesoplastron 100 Length of mesoplastron 80 Width of anal notch (between tips of xiphiplastra) 115 80

chupacabrachelys

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